To help bridge the gap between the expectations of designers and the expectations of end users of complicated aerospace systems, designers could benefit by thinking more like end users, a panel of experts said July 10 at the 2017 AIAA Propulsion and Energy Forum in Atlanta.

“We have to think more like an operator to think through how this thing gets designed and maintained through its life,” said Doug Freiberg, an engineer at Pratt & Whitney.

Panelists in the “Aircraft Propulsion: The Airline Operations and MRO Perspective” session said the gap is there because the biggest manufacturers of airplane propulsion systems are companies like GE Aviation or Pratt & Whitney — not airlines. And, Freiberg said, airlines have continually raised their expectations for ease of integrating new propulsion systems into their fleets.

“We’re no longer able to just throw the engine over the wall to the maintainers,” he said. “We’re also getting the airlines involved sooner.”

On the end user side, Robert D. Schultz, director of engine maintenance at Delta TechOps, explained, “When we look at the overall design for an engine — performance, reliability — those things are always optimized. But sometimes what can be left off to the side and not focused on enough is ease of maintenance.”

Schultz stressed the difficulty of supporting a complex fleet where the average age of an airplane is 17 years old.

“As an aircraft ages, you can really run into issues with trying to get material,” he said.

Participants in the panel discussion, "Aircraft Propulsion: The Airline Operations and MRO Perspective," July 10 during the 2017 AIAA Propulsion and Energy Forum in Atlanta.

Steve Justice, executive director of the Georgia Centers of Innovation, said, “Propulsion technology is a key to the efficiency of new airframes, but also to keeping old airplanes efficient in their operation.”

Shawn Gregg, general manager of propulsion engineering at Delta TechOps, highlighted another difference between designers and end users.

“The time scales that we work with on the operator side are much different than what you see on the design side,” Gregg said.

Research and development focuses on problems that are a decade away, he said, adding that for airline maintenance problems, “the time scale we are dealing with is right now, right at this immediate minute.”

John Kinney, director of advanced technology business development at GE Aviation, explained that there isn’t yet a precedent for how to maintain the newest technologies, which can cause tension between engineering and maintenance of aircraft propulsion systems.

“The things they do to make them more efficient for fuel burn or for emissions or for environmental are going to drive more challenges on the repair side,” Kinney said.